The city has boosted foot patrols in high-crime areas and is adding again to a downsized police force. It's too soon to say whether that explains a 33 percent drop in the homicide rate – or whether the improvement can be sustained.

Chicago — Chicago homicides are down this year after the headline-grabbing spike of 2012, which surpassed 500 gun deaths and was the deadliest crime wave in four years.

The improvement comes despite a bloody and violent January, which saw 42 homicides, making it the worst first month of the year since 2002.

But such violent crime declined sharply in the city since then, according to Chicago Police Department figures. As of June 2, total homicides for the year were down 33 percent compared with the same period last year.

The drop comes amid concerted efforts by police and city government to target 10 "hot zones" on the city's South and West sides, where street violence is most prevalent, and to enlarge the police force. Still, it is too soon to draw a direct correlation between the new crime-fighting strategies and the drop in the homicide rate, many experts say.

Because homicide counts commonly fluctuate, a full understanding of factors that drive overall crime trends requires examining statistics over a long stretch, not month-to-month, or even year-to-year, they say. Indeed, the high murder count in 2012 may prove to be an outlier: The 2013 year-to-date homicide count, while much lower than in 2012, represents only a 2 percent drop from the same period in 2011, police data show.

“We could look at last year as an aberration … or [the latest figures] might show aggressive police practices and social network-driven strategies have been showing, at last, a promising effect in reducing violence in communities where gang activity is most rampant,” says Arthur Lurigio, a criminal justice professor at Loyola University in Chicago. “It could be both. This is really a phenomenon we need to view from the long haul.”

In January, Chicago police switched their strategy, moving away from large sweeps of gang members, who are suspected of perpetrating gun violence, to adding 200 officers to night-time patrols of 10 targeted high-crime pockets. Chicago Police Superintendent Garry McCarthy says he now wants to expand the effort to 20 such hot zones.

There is also a heightened focus on manpower. When Chicago Mayor Rahm Emanuel took office in 2011, the number of officers on the streets dropped 11 percent from five years prior. Since then, budget cuts resulted in eliminating 1,400 department jobs. After last summer's violence, Mr. Emanuel pushed for hiring 500 new officers in 2013; this month, the police academy graduated its largest class since 2005.

But the officers added to hot-zone night patrols are working overtime hours to do so, raising questions about whether the new strategy is financially sustainable. Pat Camden, a spokesman for the Fraternal Order of Police, says it's not. Moreover, he is critical of the practice of sending new recruits out on foot patrol in such areas, saying they lack experience to deal with situations that are among the most dangerous.

“They’ve balanced the budget on the back of public safety when they came in, eliminating 1,400 officers. And [they] still haven’t made that up,” Mr. Camden says of city leadership. He also notes that there's been no improvement in the rate of solving homicide cases, which he describes as “pathetic.”

Mr. McCarthy, the police superintendent, asserts that the strategies have in fact helped to reduce the murder rate. Whether improvements can be sustained is tied to curbing gun violence, something he sees as dependent upon a state and federal crackdown on illegal gun sales. "The number of guns we continue to recover shows more needs to be done to stem the flow of illegal firearms," he said in a statement.